The shipment of low density material is generally costly if the low density nature of the material is retained during shipping and/or storage operations, referred to hereinafter as "subject events." Thus, where feasible, low density materials are compressed to raise the density, inter alia to reduce the volume, for these subject events which do not depend on the density for successful completion.
In some cases, the low density is desirably recovered when the subject event is completed. In other cases, the density is not particularly important after the subject event. This practice of changing the density for the subject event is cost effective so long as the cost of the subject event is reduced enough to offset the cost of increasing the density before, and potentially recovering the low density after, the subject event.
As a way of illustrating the processing of baled material, this application focuses on use of the invention to operate on bales of waste paper in recycling paper to make pulp.
As used herein, the bales of waste paper typically comprise ordinary sheets of 81/2 by 11 inch office paper, and the like, along with other light weight papers up to about 70 pounds per 3000 square foot ream. While any given system can process a variety of paper waste, the products and processes used in the pulping operation, and the products made therefrom generally suggest a primary sort before baling, whereby a given bale is limited to particular classes, or types of paper. For example, a first category of paper which can be baled together is office paper, which is generally light weight, predominantly white, and uncoated. A second category might be unbleached, single layer paper. A third category might be multiple layer corrugated paper. Other categories can be selected as desired.
In processing waste paper, the paper is generally baled at or close to the point of assembly in order to minimize the cost of shipping it to the pulping plant. At the pulping plant, the paper is stored as bales to take advantage of its density in minimizing the cost of storage until the bale is to be used. However, when the bale is to be fed into the pulping unit, it is important that the bale be broken open and dispersed as smaller size elements, and that it be fed into the pulping unit in a relatively lower density, continuous feed stream.
This invention focuses on the process of receiving bales of paper intermittently, transforming the bale into a relatively lower density, continuous feed stream, and delivering the continuous feed stream to the pulping unit.
When a bale is to be used, the cord, wire, etc., holding the bale together is removed, thus breaking the bale open. The bale elements which result from breaking the bale open are then placed on a conveyor, in a bale feeding system, which feeds the paper, as raw material, into the pulping unit.
In feeding raw material into a continuous-feed pulping unit, it is important to control the amount of feed, and the rate of feed. Thus, the paper going into the pulping unit should have a relatively constant density, and it should be fed at a relatively constant rate. A desirable feed system thus corresponds to a constant stream of paper being fed into the pulping unit at a constant depth and density on a feed conveyor.
When the bales of waste paper are broken open, the bale may fragment into components which are smaller than the bale but larger than the original pieces of paper. These components are referred to herein as bale "elements." It is, however, contemplated that the broken bale may retain its general shape, with entanglement of the individual pieces of paper holding it more-or-less together.
In either case, it is usually necessary to further break the bale down into smaller elements and to arrange the paper on the feed conveyor in a generally uniform layer.
It is an object of this invention to provide a feed system for feeding bales of paper into a pulping or other processing unit.
It is a further object to provide, in the feed system, apparatus for receiving an intermittent feed of individual bales of paper, breaking each bale into elements and dispersing it on the corresponding conveyor, and thus providing a relatively constant feed stream of paper going into the pulping unit.
It is yet another object to provide conveying apparatus, and a dispersing wheel over the conveying apparatus, which breaks the bale into smaller elements and creates a relatively constant feed stream for feeding into the pulping unit.
Another object is to provide methods of feeding bales of paper into a processing unit.
Still another object is to provide methods of breaking up and dispersing bales of paper on a conveyor.